Cryogenic tank

ABSTRACT

A substantially rectilinear tank for the storage of cryogenic fluids or the like wherein corrugated baffle plates are oriented with respect to each other and to the sideplates of the tank to provide maximum support both for the pressures built up when the container is in use and the pressures exerted on the structure during fabricating processes.

United States Patent [72] Inventor Vernon N.Trarnont1ni 1ndianapolis,1nd. [211 App]. No. 832,536 [22] Filed Apr. 29, 1969 Division of Ser. No. 582.308, Sept. 27, 1966,

Pat. No. 3,470,606

[45} Patented Aug. 31,1971 [73] Assignee Stewart-Warner Corporation Chicago, Ill.

{54] CRYOGENIC TIANK 1 Claim, 6 Drawing Figs.

[52] U.S. C1 220/71,

220/22 [51 int. Cl B65d 7/42 [50] Field oi'Search 220/71, 20,

[56] References Cited UNITED STATES PATENTS 2,358,190 9/1944 Theriault 220/22 2,986,379 5/1961 Kramig, Jr. 165/166 3,441,164 4/1969 David l-J Wang 220/71 X 3,463,222 8/1969 Grames 165/166 X Primary Examiner-Raphael H. Schwartz Attorneys-Augustus G. Douvas, William .1. Newman and Norton Lesser ATENTED AUGBI 197;

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- CRYOGENIC TANK This is a division of Application Ser. No. 582,308, filed Sept. 27, 1966 now U. S. Pat. No. 3,470,606.

The present invention relates to a cryogenic tank adapted to be used with a truck, railway car or the like for transporting a refrigerated liquified gas such as nitrogen, and to a method of tank. The transverse portions of the plates, which are spaced about 8 inches apart, strengthen the tank against burst and prevent sloshing of the liquid therein. This tank, in turn, is supported within an outer housing, and a vacuum is maintained, and insulation provided, in the space between the tank and the housing. This arrangement has proved unsatisfactory because of the extensive number and length of exposed weld seams in the tank. When the slightest crack develops along any seam, the surrounding vacuum is lost and the liquid in the tank soon boils off because of the excessive heat leak.

It is an object of the present invention to provide a cryogenic tankQand a method of making the same, wherein the number and length of external weld seams is maintained at a minimum.

It is another object of the present invention to provide a cryogenic tank, and a method of making the same, wherein substantially all of the parts thereof are joined together in a brazing operation.

It is another object of the present invention to provide a cryogenic tank, and a method of making the same, comprised of sidewalls and a plurality of corrugated baffle plates so arranged therebetween that the strength of the corrugations may be utilized during assembly without affecting reinforcement by the bafile plates of the sidewalls in the final assembly.

It is a further object of the present invention to provide a cryogenic tank, and a method of making the same, wherein strips of brazing foil are folded over the edges of the baffle plates prior to arranging them between the sidewalls in order to accomplish the brazing.

Now, in order to acquaint those skilled in the art with the manner of constructing and using cryogenic tanks in accordance with the principles of the present invention, there will be described in connection with the accompanying drawings a preferred embodiment of the invention.

In the drawings:

FIG. 1 is a perspective view of a cryogenic tank embodying the principles of the present invention;

FIG. 2 is a sectional view, on an enlarged scale and with certain portions being broken away, taken substantially along the line 22 in FIG. 1, looking in the direction indicated by the arrows;

FIG. 3 is a fragmentary sectional view, on a further enlarged scale, taken substantially along the line 33 in FIG. 2, looking in the direction indicated by the arrows;

FIG. 4 is a view, partly in section and partly in elevation and on a slightly reduced scale, taken substantially along the line 4-4 in FIG. 2, looking in the direction indicated by the arrows;

FIG. 5 is a fragmentary sectional view illustrating a portion of a tank module in a preassembly stage; and

FIG. 6 is a fragmentary and elevational view of the portion of the tank module of FIG. 5.

Referring now to FIG. 1, there is indicated generally by the reference numeral 10 a rectangular cryogenic tank constructed in accordance with the principles of the present invention. The tank 10 is preferably composed of two modules or sections 12 and 14 which, as will be presently explained, are first fabricated individually and then joined together.

As shown in FIGS. 1-4, the module 12 is comprised of a pair of flat rectangular parallel side panels 16 and 18 presenting peripheral edges, a plurality of baffle plates or fins 20 extending between. the panels, and formed end wall portions 22, 24 and 26 extending between and along three edges of the panels whereby the module presents one open end. To be noted is that the baffle plates 20 are each formed with a plurality of parallel corrugations that are arranged to extend perpendicular to the side panels 16 and 18. In addition, angle bars 28 and 30 are disposed along the edges of the side panels 16 and 18 adjacent the open end of the module 12, and pairs of angle strips 32 are located lengthwise of the end wall portions 22, 24 and 26.

Although the module 12 is used in an upright position with the side panels 16 and 18 extending vertically, during fabrication the module is laid on its side with the side panels disposed horizontally as shown in FIGS. 5 and 6. In the assembly operation, strips of brazing foil 34 are folded over the side edges of the baffle plates 20 and the latter are arranged between the side panels 16 and 18 with the brazing foil in contact with the panels. The bafi'le plates 20 are maintained in spaced relation by means of lateral locating tabs 36 punched therefrom at staggered locations in alternative plates. Also, the end wall portions 22, 24 and 26, the angle bars 28 and 30, and the angle strips 32 are located in the relative positions shown in FIGS. 1-4, and suitable brazing foil or wire is disposed along the edges of the foregoing parts. The abutting edges of the end wall portions 22 and 24, and 24 and 26, are preferably welded together, and tack welding may be performed at spaced locations to maintain the side panels, end wall portions, angle bars and angle strips in proper position prior to brazing.

Preparatory to the brazing operation and while the lower side panel 16 (FIGS. 5 and 6) is supported on a platform 38, a weighted member or grating 40 is placed on the upper side panel 18 whereby compressive forces are applied to the outer faces of the side panels 16 and 18. The described assembly is then immersed in a fluxing salt bath in a furnace, and the brazing foil is heatedto proper brazing temperature. Finally, the assembly is removed from the salt bath, air cooled rapidly for heat treating and water quenched to aid in salt removal. During the brazing operation, the side edges of the baffle plates 20 are joined to the inner faces of the side panels 16 and 18, and the other parts of the module 12 are similarly joined together. If desired, the end wall portions 22, 24 and 26 may be joined to the side panels 16 and 18 by welding rather than brazing.

The module 14 is assembled and fabricated in a brazing operation in the same manner as the module 12. Therefore, a detailed description thereof is deemed unnecessary. Like reference numerals followed by the subscript letter a have been used to indicate those parts of the module 14 that are the same as or similar to the parts of the module 12.

In the final stages of tank assembly, brackets 42 and 44 (FIGS. 2 and 3) are tack welded to the angle bar 30 of the define the tank end walls. To complete the tank 10, a bellows filler neck 50 is disposed through the end wall portions 22 and 22a at the junction thereof and is suitably secured in position as by welding. As will be appreciated from the foregoing description, the number and length'of external weld seams is maintained at a minimum, thereby reducing the risk of leaks and improving the service life of the tank.

In the above-described tank construction, the corrugations of the baffle plates 20 extend perpendicular to the side walls of the tank. This arrangement of the corrugations offers complementary advantages. On the one hand, the corrugations serve to rigidify-the bafile plates so that the latter will withstand the compressive forces applied during the brazing operation when the modules are laid on their sides. On the other hand, they do not interfere with reinforcement by the baffle plates on the sidewalls when the tank is filled with liquid under pressure. Contrastingly, if the corrugations were arranged parallel to the sidewalls, they would not reinforce the sidewalls; the walls would bulge out under internal pressure and the corrugations would thereby be straightened as in an accordion being extended. In the present construction, the rigidifying qualities of the corrugations are utilized during assembly, and yet the corrugations are oriented so as to prevent any accordion effect in the final assembly. The baffle plates also serve in a conventional manner to prevent sloshing of liquid within the tank.

Additionally, the use of strips of brazing foil folded over the edges of the baffle plates simplifies the preparation for brazing and effects more uniform brazing that contributes to improved tank strength. Finally, the angle bars 28 and 28a and 30 and 30a serve to retain the bafile plates 20 in position during the brazing operation, the angle bars 28 and 28a back up the abutting edges of the side panels during welding of the modules 12 and 14 together, and the angle bars add structural strength to the center portion of the tank where there are no baffle plates.

For storage of liquid nitrogen, and consistent with safety, a tank should withstand an internal pressure upto 200 p.s.i. A 400-gallon tank of the present invention that satisfactorily meets this requirement has the following general specifications. The tank has a height ofabout 76 inches, a width of about 80 inches and a depth of about 18 inches; the various parts of the tank are made of 6061 aluminum; the side panels, formed end wall portions and angle bars and strips have a thickness of 0.125 inch, the baffle plates a thickness of 0.020 inch,'and the braze foil a thickness of 0.003 inch; and the baffle plates are spaced 1- /4 inches apart with the amplitude of the corrugations being inch and the wave length 6 inches. The foregoing general specifications are given for illustrative purposes only. It should be appreciated that the overall dimensions may be varied to provide tanks of modified external configuration or of smaller or larger capacity, and that the other specifications may be varied relatively to accommodate the same, or lower or higher, internal pressures. The tank 10 is preferably preassembled in two sections because of size and also to permit the filler tube 46 to be centrally located as disclosed herein. Finally, the tank 10 is normally mounted in a thermally insulated outer housing. However, such a housing has not been shown or described in detail because it does not form part of the present invention.

While there has been shown and described a preferred embodiment of the present invention, it will be understood by those skilled in the art that various rearrangements and modifications may be made therein without departing from the spirit and scope of the invention.

I claim:

1. A cryogenic tank fabricated of two modules, each of said modules being comprised of a pair of flat rectangular parallel side panels with a plurality of baffle plates extending therebetween and with end wall portions extending between and along three edges of said side panels whereby the module presents one open end, the end wall portions adjacent the ends of said baffle plates being shaped to form communication passages between the spaces formed by said baffle plates, said baffle plates each having side edges adjacent said side panels and being formed with a plurality of parallel corrugations arranged perpendicular to said side panels, said end wall portions and said side edges of said baffle plates being joined to said side panels in a brazing operation performed while compressive forces are applied to said side panels, said corrugation of said baffle plates serving to rigidify said baffle plates so that the latter will withstand the compressive forces applied during the brazing operation, said modules being secured together at their open ends to provide a closed tank, and means forming an inlet in one of said end wall portions adjacent one end of said bafile plates. 

1. A cryogenic tank fabricated of two modules, each of said modules being comprised of a pair of flat rectangular parallel side panels with a plurality of baffle plates extending therebetween and with end wall portions extending between and along three edges of said side panels whereby the module presents one open end, the end wall portions adjacent the ends of said baffle plates being shaped to form communication passages between the spaces formed by said baffle plates, said baffle plates each having side edges adjacent said side panels and being formed with a plurality of parallel corrugations arranged perpendicular to said side panels, said end wall portions and said side edges of said baffle plates being joined to said side panels in a brazing operation performed while compressive forces are applied to said side panels, said corrugation of said baffle plates serving to rigidify said baffle plates so that the latter will withstand the compressive forces applied during the brazing operation, said modules being secured together at their open ends to provide a closed tank, and means forming an inlet in one of said end wall portions adjacent one end of said baffle plates. 